Modular photocatalytic air purifier

ABSTRACT

A photocatalytic air purifier is disclosed. The photocatalytic purifier includes filter structures coated with a catalytic material such as titanium dioxide. One or more UV lamps are interposed between the filter structures. The catalytic layer reacts with airborne VOCs and bioaerosols when activated by the UV lamps to thereby oxidize the VOCs and destroy the bioaerosols. The photocatalytic air purifier does not need to be replaced or regenerated after a period of continuous usage. The photocatalytic purifier of the present invention substantially eliminates odors, VOCs, and bioaerosols from air directed through the fan coil. The photocatalytic air purifier includes a control system that optimizes operating costs. Because of these features, service, maintenance, and filter replacement are reduced to a minimum. At the same time, the well being of persons living in the space conditioned by the photocatalytic air purifier is improved.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to air purifiers, andparticularly to photocatalytic purifiers.

2. Technical Background

Most fan coil units consist of a water coil or a direct expansion coil,a fan, and ductwork to distribute conditioned air. Before heating orcooling, air is directed through a filter of some sort. There arevarious types of filters. One type of filter is referred to as a mediafilter. This type of filter retains dust and other particulate matter.After prolonged usage, media filters become clogged and need to bereplaced.

Another type of filter currently being used is known as a HEPA filter.HEPA is an acronym for “high efficiency particulate air.” HEPA filterscan capture 99.9% of all particles, including sub-micron sizedparticles. These filters are useful in mitigating the effects ofbioaerosols and dust. They are currently being used in hospitals,manufacturing clean rooms, and in other applications where clean air isconsidered vital. Typically, HEPA filters have an operational life spanof twenty-four (24) months. After that, efficiency decreases markedly,and HEPA filters must be replaced.

Another type of filter currently being used are activated carbonadsorption filters. These filters were developed in response toindustrial emissions of volatile organic compounds (VOCs). In anactivated carbon adsorption system, contaminated air is directed acrossa bed of carbon. The carbon extracts the VOCs from the air and adsorbsthe VOCs by holding them to its surface. One problem with activatedcarbon adsorption filters is that the air stream being filtered cannothave a high moisture content because carbon adsorbs moisture. Air havinga high moisture content will quickly fill the carbon bed to capacity.Second, the air being filtered cannot include a large amount ofparticulate matter. The particulate matter will also clog the carbonbed. Thus, the activated carbon adsorption filter may require apre-filter to reduce the particulate content and a dehumidifier toreduce moisture content to be effective.

An air filter is needed that substantially eliminates odors, VOCs, andbioaerosols from an air mass without requiring extensive service ormaintenance. A need exists for a photocatalytic air purifier that can beconveniently installed and removed for maintenance purposes.

SUMMARY OF THE INVENTION

The present invention is directed to a photocatalytic air purifier thatcan be conveniently installed and removed for maintenance purposes. Thephotocatalytic purifier of the present invention substantiallyeliminates odors, VOCs, and bioaerosols from air that is directedthrough a duct or a fan coil. The photocatalytic air purifier of thepresent invention is suitable for both commercial and residentialapplications and can be installed in either original equipment orretrofitted into existing instalations.

One aspect of the present invention is a modular photocatalytic airpurifier. The photocatalytic purifier including a modular enclosurehaving a retractable alignment mechanism. The retractable alignmentmechanism is configured to move the modular enclosure between an in-useposition aligned within the fan coil unit and a retracted position. Aplurality of support structures are disposed within the modularenclosure, each of the plurality of support structures having acatalytic layer disposed thereon. At least one UV lamp is interposedbetween the plurality of support structures.

In another aspect, the present invention includes a fan coil unit havingan air return, a coil unit, a fan, and an air supply. The fan coil unitincludes at least one photocatalytic purifier disposed adjacent the coilunit. The at least one photocatalytic purifier includes a modularenclosure having a retractable alignment mechanism. The retractablealignment mechanism is configured to move between an in-use positionaligned within the fan coil unit and a retracted position. A pluralityof support structures are disposed within the modular enclosure, each ofthe plurality of support structures having a catalytic layer disposedthereon, and at least one UV lamp interposed between the plurality ofsupport structures. A control unit may be coupled to the at least onephotocatalytic purifier, whereby the control unit energizes the at leastone UV lamp in accordance with a fan coil operating mode.

In yet another aspect, the present invention includes a method forfiltering air in a unit having an air return, and an air supply. Themethod includes providing at least one modular photocatalytic purifier.The at least one photocatalytic purifier includes a modular enclosurehaving a retractable alignment mechanism, and at least one UV lampinterposed between a plurality of titanium dioxide coated filterstructures. The retractable alignment mechanism is used to dispose theat least one modular photocatalytic purifier in an in-use positionwithin the unit. Air is directed from the air return into the at leastone photocatalytic purifier. Contaminants borne by the air are broughtinto contact with the titanium dioxide coated filter structures. UVradiation is directed from the at least one UV lamp onto the titaniumdioxide coated filter structures, whereby the titanium dioxide coatedfilter structures are activated to react with the contaminants toproduce carbon dioxide and water.

Additional features and advantages of the invention will be set forth inthe detailed description which follows, and in part will be readilyapparent to those skilled in the art from that description or recognizedby practicing the invention as described herein, including the detaileddescription which follows, the claims, as well as the appended drawings.

It is to be understood that both the foregoing general description andthe following detailed description are merely exemplary of theinvention, and are intended to provide an overview or framework forunderstanding the nature and character of the invention as it isclaimed. The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated in and constitute apart of this specification. The drawings illustrate various embodimentsof the invention, and together with the description serve to explain theprinciples and operation of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a photocatalytic purifier in accordance withthe present invention;

FIG. 2 is a cross-sectional view of the photocatalytic purifier takenthrough line A—A in FIG. 1;

FIG. 3 is a detail view of the honey-combed filter element depicted inFIG. 2;

FIG. 4 is a diagrammatic depiction of a fan coil unit in accordance witha first embodiment of the invention showing the photocatalytic purifierdepicted in FIGS. 1-3 in an in-use position;

FIG. 5 is a diagrammatic depiction of a fan coil unit in accordance withthe first embodiment of the invention showing the photocatalyticpurifier depicted in FIGS. 1-3 in a retracted position; and

FIG. 6 is a diagrammatic depiction of a fan coil unit in accordance witha second embodiment of the invention showing the photocatalytic purifierdepicted in FIGS. 1-3 in a retracted position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the present preferredembodiments of the invention, examples of which are illustrated in theaccompanying drawings. Wherever possible, the same reference numberswill be used throughout the drawings to refer to the same or like parts.An exemplary embodiment of the photocatalytic purifier of the presentinvention is shown in FIG. 1, and is designated generally throughout byreference numeral 10.

In accordance with the invention, the present invention includes aphotocatalytic air purifier for use in a fan coil unit or a duct. Thepurifier features a modular enclosure having a retractable alignmentmechanism. The retractable alignment mechanism is configured to move theenclosure between an in-use position aligned within the fan coil unitand a retracted position. The photocatalytic purifier includes a firsthoney-combed filter structure having a catalytic layer disposed thereon.A second honey-combed filter structure is disposed adjacent to the firsthoney-combed filter structure, the second honey-combed filter structurealso having the catalytic layer disposed thereon. At least one UV lampis disposed between the first honey-combed filter structure and thesecond honey-combed filter structure. The catalytic layer reacts withairborne VOCs and bioaerosols when activated by UV light to therebyoxidize the VOCs and destroy the bioaerosols.

Thus, the photocatalytic purifier of the present invention substantiallyeliminates odors, VOCs, and bioaerosols from air directed through a fancoil while reducing service and maintenance to a minimum. Further, thephotocatalytic air purifier is conveniently installed and removed formaintenance purposes.

As embodied herein and depicted in FIG. 1, a plan view of aphotocatalytic purifier in accordance with the present invention isdisclosed. Photocatalytic purifier 10 is disposed in fan coil housing102, between media filter 50 and fan coil unit 30. One of ordinary skillin the art will recognize that this embodiment of the present inventioncan also be employed in a duct system instead of a fan coil unit.Photocatalytic purifier 10 includes at least one filter layer 12 havingat least one UV lamp 20 disposed between honey-combed filter element 14and honey combed filter element 16. In the embodiment depicted in FIG.1, a second photocatalytic purifier layer 12′ is formed by disposing UVlamps 22 between filter element 16 and filter element 18. Eachadditional filter layer 12 increases the efficiency of filter 10. Thus,photocatalytic purifier 10 may include a plurality of filter layers 12that include at least one UV lamp 20 disposed between honey-combedfilter elements 14 and 16.

FIG. 2 is a cross-sectional view of filter 10 taken through line A—A inFIG. 1. The cross-sectional view clearly shows the honey-combedstructure of filter element 12. Any suitable structure may be employed,however, the honey-combed structure of filter elements 12, 14, and 16 ispreferred because air pressure is maintained as air is directed throughfilter 10. Filter elements 12, 14, and 16 include catalytic coating 120disposed thereon. As depicted in FIG. 2, UV lamps 20 are positioned todirect UV radiation into the interior of honey-combed filter elements 12and 14. As shown in FIG. 2, the cross-section of photocatalytic purifier10 is equal to the cross-section of fan coil housing 102. Thus, purifier10 purifies the entire volume of air passing through the fan coil.

FIG. 3 is a detail view of honey-combed filter element 12, showingcatalytic coating 120 and substrate 122. One of ordinary skill in theart will recognize that any suitable catalytic coating 120 may bedisposed on elements 12, 14, or 16, but there is shown by way of examplea coating of titanium dioxide. One of ordinary skill in the art willalso recognize that any suitable material may be used as a substratematerial for filter elements 12, 14, and 16, but there is shown by wayof example a ceramic substrate. In other embodiments, an aluminumsubstrate or an FeCrAlY alloy substrate are used. Both the ceramic andaluminum substrates are desirable in applications requiringnon-flammable filter elements. If non-flammability is not an issue,substrate 122 used in filter elements 12, 14, and 16 could be fabricatedusing a paper material. One of ordinary skill in the art will alsorecognize that any suitable substrate geometry may be used. The geometrycan include honey-combs, fins, mesh, a filter-type structure, a fibroustype, or a filamentous structure.

Photocatalytic purifier 10 employs photocatalytic oxidation technologyto substantially eliminate odors, VOCs, and bioaerosols. Air propagatingthrough purifier 10 passes over catalytic layer 120. In gas-solidphotocatalytic oxidation (PCO), a VOC laden air stream is brought intocontact with a titania catalyst disposed on layer 120. The UV lightactivates the catalyst. The VOCs react with the activated catalyst andare converted into carbon dioxide and water via oxidation. This processoccurs at room temperature. Since the process occurs at roomtemperature, the operating cost is much lower than conventional hightemperature thermal oxidizers. PCO destroys a wide range of contaminantsin air streams. Filter elements 14, 16, and 18 are not degraded overtime by UV light and thus, they do not need to be replaced even aftercontinuous prolonged usage. It should also be mentioned that bioaerosolsare also destroyed by their exposure to UV light.

As embodied herein, and depicted in FIG. 4, fan coil unit 100 includeshousing 102 which is connected to suspension casing 104. Suspensioncasing 104 is attached to a ceiling or some other structural element ofthe building accommodating fan coil unit 100. Fan coil unit 100 includesphotocatalytic purifier 10 which is disposed in housing 102 betweenmedia filter 50 and fan coil 30. Fan coil 30 includes cold water supply34 and hot water supply 36. Both cold water supply 34 and hot watersupply 36 include valves (not shown) that are controlled by fan coilcontroller 110 to thereby regulate heating and cooling within theconditioned space. Fan coil unit 100 also includes fan 32 which draws anair stream from air return 42 through photocatalytic purifier 10 and fancoil 30. The air stream is then directed into the conditioned space viaair supply duct 40. In FIG. 4, photocatalytic purifier 10 is shown inthe in-use position, being disposed adjacent to filter 50.Photocatalytic purifier 10 includes modular enclosure 60 having aretractable alignment mechanism 62. Retractable alignment mechanism 62is configured to move enclosure 60 between an in-use position alignedwithin the fan coil unit, and a retracted position. In this embodiment,alignment mechanism 62 is a hinged door structure. Mechanism 62 includesarm 64 that is used to hold enclosure 60 in the in-use position. Theretracted position is depicted in FIG. 5.

An alternative embodiment is a sliding arrangement wherein thephotocatalytic purifier 10 can be made to slide from its installedposition to a retracted position as shown by the dashed lines in FIG. 4

It will be apparent to those of ordinary skill in the pertinent art thatmodifications and variations can be made to fan coil control 110 of thepresent invention depending on cost requirements and the complexity ofthe application. For example, fan coil unit 100 can be deployed as astand-alone unit in a single family dwelling, or as one unit among manyin a complex architecture. For example, fan coil unit 100 may beemployed in a multi-storied structure having a plurality ofair-conditioned zones. Fan coil control 110 includes firmware containingthe control program necessary to control the water valves, fan 32, andUV lamps 20, 22, and 24 included in photocatalytic purifier 10. Thecontrol program is executed by an embedded microprocessor included infan coil control 110. In another embodiment, fan coil control 110 isimplemented using a logic controller.

Fan coil control 110 includes several operational modes 80 that areselected by a switch 81. The first mode is an “unoccupied mode.” In thismode, the level of comfort provided by fan coil unit 100 does not haveto be at an optimum level because no one is in the conditioned space asdetermined by the sensor 82. The heating and cooling of the airconditioned zone is regulated in accordance with a wider “dead-band.”Thus, controller 110 allows the ambient air temperature of the airconditioned zone to vary within a wide range temperatures beforeproviding either heating or cooling. The UV lamps are generallyinoperative during this mode but may be on for some lead/lay time beforeor after occupency.

The second mode is referred to as the “occupied mode.” In this mode, thelevel of comfort provided by fan coil unit 100 is optimized because ofthe presence of people in the conditioned space. Thus, the UV lamps arealways operating in this mode. The occupied mode includes a “demand”sub-mode wherein fan 32 is operating at a higher speed, and a“satisfied” sub-mode wherein fan 32 is operative at a lower speed. Inother embodiments, controller 110 uses a “tolerance index” as a controlmetric. Controller 110 may include a motion detector input to determinewhether the conditioned space is occupied.

A third mode is provided by controller 110. It is known as the “frostprotection mode.” The frost protection mode initiates heating within aconditioned space only to maintain a minimum air temperature within theair conditioned space. Since the air conditioned space is assumed to beunoccupied, the UV lamps are not operative in this mode. In addition totemperature sensors 86, controller 110 may include a sensor 87 inputcoupled to window contacts, enabling it to recognize an open windowcondition. In another embodiment, the frost protection mode initiatesheating during the open window condition. An indoor air quality (IAQ)sensor 88 provides feedback to the fan coil control 110 as to thequality of air in the particular zone being conditioned.

As embodied herein and depicted in FIG. 5, a diagrammatic depiction offan coil unit 100 showing photocatalytic purifier 10 in a retractedposition is disclosed. In the retracted position, hinged door structure62 retracts to provide access to purifier 10 during maintenance or theremoval of purifier 10. Arm 64 is detached from purifier 10 duringremoval.

As embodied herein and depicted in FIG. 6, a diagrammatic depiction ofphotocatalytic purifier unit 100 in accordance with a second embodimentof the invention is disclosed. In this embodiment, unit 100 is disposedin media cabinet 70. The enclosure 60 of photocatalytic purifier 10 isshown in a retracted position. Enclosure 60 is equipped with slidermechanism 72 on a top portion of enclosure 60, and is equipped withslider mechanism 74 on a bottom portion of enclosure 60. One of ordinaryskill in the art will recognize that unit 100 can be a fan coil unit orpart of a duct system.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the present inventionwithout departing from the spirit and scope of the invention. Thus, itis intended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. A modular photocatalytic air purifier, the photocatalytic purifiercomprising: a modular enclosure having a retractable alignmentmechanism, the retractable alignment mechanism being configured to movebetween an in-use position and a retracted position; a plurality ofsupport structures disposed within the modular enclosure, each of theplurality of support structures having a catalytic layer disposedthereon; and at least one UV lamp interposed between the plurality ofsupport structures.
 2. The photocatalytic air purifier of claim 1,wherein the catalytic layer is comprised of titanium dioxide.
 3. Thephotocatalytic air purifier of claim 1, wherein the plurality of supportstructures are comprised of a ceramic fiber substrate.
 4. Thephotocatalytic air purifier of claim 1, wherein the plurality of supportstructures are comprised of a non-flammable substrate.
 5. Thephotocatalytic air purifier of claim 4, wherein the plurality of supportstructures are comprised of a ceramic substrate.
 6. The photocatalyticair purifier of claim 4, wherein the plurality of support structures arecomprised of an aluminum substrate.
 7. The photocatalytic air purifierof claim 1, wherein the catalytic layer is adapted to react withairborne volatile organic compounds and airborne bioaerosols flowingthrough the photocatalytic purifier when activated by the at least oneUV lamp.
 8. The photocatalytic air purifier of claim 7, wherein the atleast one UV lamp oxidizes volatile organic compounds in contact withthe catalytic layer.
 9. The photocatalytic air purifier of claim 7,wherein the at least one UV lamp destroys bioaerosols in contact withthe catalytic layer.
 10. The photocatalytic air purifier of claim 1,wherein the plurality of support structures are comprised of ahoney-combed material.
 11. The photocatalytic air purifier of claim 1,wherein the plurality of support structures include a fin structure. 12.The photocatalytic air purifier of claim 1, wherein retractablealignment mechanism includes a hinged door structure configured to beretracted to provide access to the modular photocatalytic air purifier.13. The photocatalytic air purifier of claim 12, wherein retractablealignment mechanism includes a support arm to hold the hinged doorstructure in place during installation and removal of the photocatalyticair purifier.
 14. The photocatalytic air purifier of claim 1, whereinretractable alignment mechanism includes a sliding mechanism that isconfigured to slide the modular enclosure between the in-use positionand the retracted position.
 15. The photocatalytic air purifier of claim1, wherein the photocatalytic air purifier is disposed in a fan coilunit.
 16. The photocatalytic air purifier of claim 1, wherein thephotocatalytic air purifier is disposed in a duct.
 17. A fan coil unitincluding an air return, a coil unit, a fan, and an air supply, the fancoil unit comprising: at least one photocatalytic purifier including, amodular enclosure having a retractable alignment mechanism, theretractable alignment mechanism being configured to move between anin-use position aligned within the fan coil unit and a retractedposition, a plurality of support structures disposed within the modularenclosure, each of the plurality of support structures having acatalytic layer disposed thereon, and at least one UV lamp interposedbetween the plurality of support structures; and a control unit coupledto the at least one photocatalytic purifier and configured to energizethe at least one UV lamp in accordance with a fan coil operating mode.18. The fan coil unit of claim 17, further comprising a media filtrationfilter disposed between the at least one photocatalytic purifier and theair return path.
 19. The fan coil unit of claim 17, wherein the at leastone photocatalytic purifiers includes a plurality of photocatalyticpurifiers.
 20. The fan coil unit of claim 17, wherein the catalyticlayer is comprised of titanium dioxide.
 21. The fan coil unit of claim17, wherein the plurality of support structures are comprised of a papersubstrate.
 22. The fan coil unit of claim 17, wherein the plurality ofsupport structures are comprised of a non-flammable substrate.
 23. Thefan coil unit of claim 22, wherein the plurality of support structuresare comprised of a ceramic substrate.
 24. The fan coil unit of claim 22,wherein the plurality of support structures are comprised of an aluminumsubstrate.
 25. The fan coil unit of claim 17, wherein the catalyticlayer is adapted to react with airborne volatile organic compounds andairborne bioaerosols flowing through the fan coil unit.
 26. The fan coilunit of claim 25, wherein the at least one UV lamp oxidizes volatileorganic compounds in contact with the catalytic layer.
 27. The fan coilunit of claim 25, wherein the at least one UV lamp destroys bioaerosolsin contact with the catalytic layer.
 28. The fan coil unit of claim 17,wherein the at least one UV lamp is selectively energized in accordancewith one of a plurality of air quality modes included in the controlunit.
 29. The fan coil unit of claim 28, wherein the plurality of airquality modes comprises: an occupied mode wherein the control unit isconfigured to energize the at least one UV lamp and selectivelyenergizes the fan; and an unoccupied mode wherein the control unit isconfigured to de-energizes the at least one UV lamp while regulating thecoil to thereby maintain temperature within a predetermined temperaturerange.
 30. The fan coil unit of claim 29, wherein the occupied modefurther comprises: a demand sub-mode wherein the fan and a valve areenergized; and a satisfied sub-mode wherein at least the valve isde-energized.
 31. The fan coil of claim 28, wherein one of the pluralityof air quality modes is selected by a switch.
 32. The fan coil of claim28, wherein one of the plurality of air quality modes is selected by asensor.
 33. The fan coil of claim 32, wherein the on-demand mode isselected in response to an output of an indoor air quality (IAQ) sensor.34. The fan coil of claim of claim 17, wherein the plurality of supportstructures are comprised of a honey-combed material.
 35. The fan coil ofclaim of claim 17, wherein the plurality of support structures include afin structure.
 36. The fan coil of claim of claim 17, whereinretractable alignment mechanism includes a hinged door structureconfigured to be retracted to provide access to the modularphotocatalytic air purifier.
 37. The fan coil of claim of claim 36,wherein retractable alignment mechanism includes a support arm to holdthe hinged door structure in place during installation and removal ofthe photocatalytic air purifier.
 38. The fan coil of claim of claim 17,wherein retractable alignment mechanism includes a sliding mechanismconfigured to slide the modular enclosure between the in-use positionand the retracted position.